Surface-mountable components that are tantalum electrolytic capacitors are known from publication WO 01/16973 A1. These surface-mountable components have the disadvantage that they demonstrate an equivalent series resistance, also known under the name electrical series resistance (ESR), which is too high for many requirements.
One attempt at solving this problem requires connecting a plurality of individual components together in parallel within one surface-mountable component, the separate capacitors being surrounded by a common housing. One such component is known from U.S. Pat. No. 3,685,535. The parallel connection of individual capacitors within one single common housing has the disadvantage that production costs are high, because connecting in parallel is performed approximately at the time when the manufacturing process is half complete. Additional manufacturing steps are necessary after the parallel connections have been made. If an individual capacitor breaks down in one of these subsequent steps, the entire component will become unusable, leading to a higher rejection rate.
The object of the present invention is therefore to provide a surface-mountable component comprising of individual components solidly stacked together that may be manufactured with a low rejection rate and is particularly easy to mount, on a circuit board for example.
This object is achieved with a surface-mountable component as recited in claim 1. Other embodiments of the component and a method for its manufacture may be derived from the other claims.
A surface-mountable component that demonstrates at least one external connection shall be provided. The component moreover demonstrates individual components, which are stacked together and contain the individual terminals. Spot welds connect the external connection to a plurality of individual terminals. The external connection forms a contact surface on the assembly side of the component, an area that is free of spot welds being provided on the external connection for later wetting with solder.
The surface-mountable component has the advantage that the individual components are connected to their individual terminals with the aid of the external connection. The connection of the individual components accordingly thus takes place externally, after the particular individual component has been produced. Since spot welds connect the external connection to the individual terminals, a particularly solid, corrosion-resistant electrical connection between the external connection and the individual terminals results. An area that is free of spot welds is provided on the external connection for later wetting with solder, making it particularly easy to solder the component according to invention to a circuit board, for example. In general, spot welds have the property that they cannot be wetted with solder very well.
The term “individual terminals” is intended to mean in particular connecting terminals of the individual components that are arranged on the outside of the individual components. Since a contact surface is formed on the assembly side of the component with the aid of the external connection, a surface-mountable component may be realized in a simple way and manner.
The stacking of the individual components together furthermore has the advantage that a space-saving construction of the individual components can be achieved.
In one embodiment of the component, the external connection is designed L-shaped. One leg of the L forms the contact surface. Here it is particularly advantageous for that leg of the L that forms the contact surface to be directed inwards. This achieves a particularly space-saving construction.
In one embodiment of the component, the external connection may be formed out of one of the individual terminals. This has the advantage of potentially dispensing with the processing of additional elements.
In another embodiment of the invention, individual terminals are located only on the inside of the external connection. This embodiment of the component has the advantage that an overlap of different contact elements or pins from the outside can be avoided, including from the assembly side and from the side faces of the component that adjoin the assembly side.
The surface-mountable component is preferably pressed into prepared soldering points or conductive adhesive on a printed circuit board and then wetted with solder on its contact surfaces by means of heat. Here the wetting of the solder may only occur at the contact surfaces on the assembly side of the component. Even more, it must still be possible to wet with solder to a certain minimum height across the circuit board at the external contacts of the component. Since the external contact doesn't have any overlap with other contact elements on its outside, a particularly advantageous good wettability with solder results here.
It is furthermore advantageous for each individual component to feature its own housing.
In another embodiment of the component, the external connection is a separate part that is connected to individual terminals. This embodiment has the advantage that the external connection may be used as a forming element when assembling the component.